Rare Earth Based Hydrogen Storage Alloy and Application Thereof

ABSTRACT

The invention relates to a rare earth based hydrogen storage alloy, represented by the general formula (I): 
       RE x Y y Ni z-a-b-c Mn a Al b M c Zr A Ti B   (I)
 
     wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W. The alloy has favorable pressure-composition-temperature characteristic, high hydrogen storage capacity, high electrochemical capacity. The alloy doesn&#39;t contain magnesium element, and the preparation process of the alloy is easy and safe.

TECHNICAL FIELD

The invention belongs to the field of hydrogen storage alloy, and relates to a rare earth based hydrogen storage alloy and the application thereof.

BACKGROUND

Hydrogen storage alloy is a functional material with high hydrogen-storage density. At present, hydrogen storage alloy could be roughly divided into six categories: rare earth based AB₅ type, such as LaNi₅; magnesium based, such as Mg₂Ni, MgNi, La₂Mg₁₇; rare earth-magnesium-nickel based AB₃₋₄ type, such as La₂MgNi₉, La₅Mg₂Ni₂₃, La₃MgNi₁₄; titanium based AB type, such as TiNi, TiFe; zirconium or titanium based AB₂ type with Laves phase, such as ZrNi₂; vanadium based solid solution type as (V_(0.9)Ti_(0.1))_(1-x)Fe_(x).

The hydrogen-storage material widely used nowadays is LaNi₅ type hydrogen-storage alloy. The alloy is mainly used as a negative material of a metal hydride-nickel(MH-Ni) secondary battery, with a theoretical electrochemical capacity of about 373 mAh·g⁻¹. The commercial negative material electrode materials in actual application is Mm(NiCoMnAl)₅ (wherein Mm denotes mixed rare earths), which has a maximum capacity of 350 mAh·g⁻¹. In order to develop hydrogen-storage alloys with better electrochemical properties or higher hydrogen storage capacity, the research of magnesium based alloy has become a hotspot. Magnesium based alloys have high theoretical capacity. Especially, great progresses have been made in the study of rare earth-magnesium-nickel based AB₃ type, A₂B₇ type and A₅B₁₉ type alloys and these alloys has been put into industrial application. Titanium, zirconium and vanadium based hydrogen storage materials were not widely used due to their disadvantages such as poor activation characteristic, high cost, etc.

CN201310228766.0 discloses an A₂B₇ type hydrogen storage alloy for nickel-hydride battery and preparation method thereof. The composition of the alloy conforms to the general formula Ln_(a)Mg_(b)Ni_(x)Y_(y)Z_(z), wherein Ln denotes one or more rare earth element(s), Y denotes one or more element(s) selected from Al, Co, Nb, V, Fe, Cu, Zn, As, Ga, Mo, Sn, In, W, Si and P, and Z denotes one or more element(s) selected from Ag, Sr, Ge, 0.5≦a<2, 0<b<1, 5<X+Y+Z<9, 0<Y<3, 0<Z<1.

CN101210294A discloses a A₅B₁₉ type alloy. The alloy has a formula of X_(5-a)Y_(a)Z_(b), wherein X denotes one or more of rear earth metals, Y denotes one or more of alkaline earth metal(s), Z denotes one or more element(s) selected from Mn, Al, V, Fe, Si, Sn, Ni, Co, Cr, Cu, Mo, Zn and B, 0<a≦2, 17.5≦b≦22.5.

CN102195041A discloses a hydrogen storage alloy for an alkaline storage battery. The alloy has a formula of La_(x)Re_(y)Mg_(1-x-y)Ni_(n-m-v)Al_(m)T_(v), wherein Re denotes at least one rare earth element(s) including Y(ytterbium)(except La), T denotes at least one element(s) selected from Co, Mn and Zn; 0.17≦x≦0.64, 3.5≦n≦3.8, 0.06≦m≦0.22, v≧0. The main phase of the alloy is A₅B₁₉ type crystal structure.

CN101238231A discloses a hydrogen storage alloy. The alloy contains a phase of Pr₅Co₁₉ type crystal structure, which conforms to the general formula A_((4−w))B_((1+w))C₁₉, wherein A denotes one or more element(s) selected from rare earth elements including Y (yttrium); B denotes Mg element; C denotes one or more element(s) selected from Ni, Co, Mn, and Al; and w denotes a numeral in a range from −0.1 to 0.8; and the alloy have a composition as a whole defined by the general formula R1_(x)R2_(y)R3_(z), wherein 15.8≦x≦17.8, 3.4≦y≦5.0, 78.8≦z≦79.6, and x+y+z=100; R1 denotes one or more element(s) selected from rare earth elements including Y (yttrium); R2 denotes an Mg element, R3 denotes one or more element(s) selected from Ni, Co, Mn, and Al; z is 0.5 or higher when it denotes the stoichiometric number of Mn+Al; z is 4.1 or lower when it denotes the stoichiometric number of Al.

CN102660700A discloses an AB₃ type hydrogen storage alloy and preparation method thereof. The chemical formula of the AB₃ type hydrogen storage alloy is La_(0.35)Pr_(0.30)Mg_(x)Ni_(2.90)Al_(0.30), wherein x=0.30˜0.35.

CN102195041A discloses a hydrogen storage alloy for an alkaline storage battery, the composition of which conforms to the general formula La_(x)Re_(y)Mg_(1-x-y)Ni_(n-m-v)Al_(m)T_(v) (Re: rare earth elements including Y; T: Co, Mn, Zn; 0.17≦x≦0.64, 3.5≦n≦3.8, 0.06≦m≦0.22, v≧0), and the alloy's main phase has a A₅B₁₉-type crystal structure.

CN103326004A discloses an A₂B₇ hydrogen storage alloy for a nickel metal hydride battery and preparation method thereof. The alloy conforms to the structural general formula: Ln_(a)Mg_(b)Ni_(x)Y_(y)Z_(z), wherein Ln denotes at least one element selected from rare earth elements; Y denotes least one element selected from Al, Co, Nb, V, Fe, Cu, Zn, As, Ga, Mo, Sn, In, W, Si and P; Z denotes at least one element selected from Ag, Sr and Ge; 0.5≦a<2, 0<b<1, 5<X+Y+Z<9, 0<Y<3, 0<Z<1.

The above alloys do not contain Y element, or do not contain Zr element, or do not contain Ti element. However, they all contain alkaline earth metals or magnesium element. Because the vapor pressure of active metal element magnesium is high, the difficulty of manufacturing the alloy is increased, and the composition of the alloy is difficult to control. The escaped micro-fine magnesium powder is flammable and combustible, which is a potential safety hazards.

Researches of “An electrochemical study of new La_(1-x)Ce_(x)Y₂Ni₉ (0≦x≦1) hydrogen storage alloys” (Electrochimica Acta, 46 (2001): 2385-2393) and “New ternary intermetallic compounds belonging to the R—Y—Ni(R═La, Ce) system as negative material electrodes for Ni-MH batteries” (Journal of Alloys and Compounds, 330-332 (2002): 782-786) report an AB₃ type La—Y—Ni hydrogen storage alloy. Nevertheless, the alloy doesn't contain Mn and Al, and its maximum hydrogen storage capacity is only 260 mAh·g⁻¹.

SUMMARY

An object of the invention is to provide a rare earth based hydrogen storage alloy with high hydrogen storage capacity. Another object of the invention is to provide a rare earth based hydrogen storage alloy with high electrochemical capacity. Another object of the invention is to provide a rare earth based hydrogen storage alloy which is easy to prepare, or the composition of which is easy to control, or the preparation process of which is safe.

In order to achieve one or more of the above objects, according to the first aspect of the present application, provided is a rare earth based hydrogen storage alloy represented by the general formula (I):

RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B)   (I)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W; x>0, y≧0.5,

x+y=3, 13≧z≧7; 6≧a+b>0, 5≧c≧0, 4≧A+B≧0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), x>0, y≧0.5, x+y=3; 12.5≧z≧8.5; 5.5≧a+b>0, 3.5≧c≧0, 2.5≧A+B≧0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes La and/or Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes La.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes mischmetal consisting of La and Ce, preferably the atomic ratio of La and Ce is 0.8:0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes Lanthanum-rich mischmetal wherein La accounts for about 64 wt %, Ce accounts for about 25 wt %, Pr accounts for about 3 wt % and Nd accounts for about 8 wt %.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 2.5≧A+B>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 11>z≧9.5, 4.5≧a+b>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 12.5≧z≧11, 5.5≧a+b>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 9.5>z≧8.5; 3.5≧a+b>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A=B=0, c>0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 3.5≧a+b≧0; 3.0≧c>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0, 11>z≧9.5, 4.5≧a+b>0. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-1):

RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b)  (I-1)

wherein: RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; x>0, y≧0.5, x+y=3; 11>z≧9.5; 4.5≧a+b>0. When z=10.5, the hydrogen storage alloy is stoichiometric A₂B₇ type; when z≠10.5, the hydrogen storage alloy is non-stoichiometric A₂B₇ type.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≧x≧0.5, preferably 2.0≧x≧0.5, further preferably 1.2≧x≧0.8.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≧a≧0, preferably 2.5≧a≧0.5, further preferably 0.6≧a≧0.4.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 1.0≧b≧0, preferably 1.0≧b≧0.2, or preferably 0.3≧b≧0.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 10.8≧z≧9.5, preferably z=10.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.0≧x≧0.5, 2.5≧a≧0.5, 1.0≧b≧0.2, z=10.5.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0, 12.5≧z≧11. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-1):

RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b)  (I-1)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; x>0, y≧0.5, x+y=3; 12.5≧z≧11; 5.5≧a+b>0. When z=11.4, the hydrogen storage alloy is stoichiometric A₅B₁₉ type; when z≠11.4, the hydrogen storage alloy is non-stoichiometric A₅B₁₉ type.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≧x≧0.5, preferably 2.0≧x≧0.5, further preferably 1.5≧x≧1.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 3.0≧a≧0, preferably 3.0≧a≧0.5, further preferably 1.0≧a≧0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 1.5≧b≧0, preferably 1.5≧b≧0.3, further preferably 0.5≧b≧0;

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 12.5≧z≧11, preferably 11.4≧z≧11.0 further preferably z=11.4.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.0≧x≧0.5, 3.0≧a≧0.5, 1.5≧b≧0.3, z=11.4.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c=0, A=B=0, 9.5>z≧8.5; 3.5≧a+b>0. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-1):

RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b)  (I-1)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≧0.5, x+y=3; 9.5>z≧8.5, 3.5≧a+b>0. When z=9, the hydrogen storage alloy is stoichiometric AB₃ type; when z≠9, the hydrogen storage alloy is non-stoichiometric AB₃ type.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.5≧x≧0.5, preferably 2.0≧x≧0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2≧a≧0; preferably 2≧a≧0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 1.0≧b≧0, preferably 1.0≧b≧0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 9.5≧z≧8.5, preferably z=9.

In another further preferably embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), 2.0≧x≧0.5, 2.0≧a≧0.5, 1.0≧b≧0.2, z=9.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes La and/or Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes La.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes mischmetal consisting of La and Ce, preferably wherein the atomic ratio of La and Ce is 0.8:0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-1), RE denotes Lanthanum-rich mischmetal, La accounts for about 64 wt %, Ce accounts for about 25 wt %, Pr accounts for about 3 wt % and Nd accounts for about 8 wt %.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A=B=0, 3.5≧a+b≧0; 3.0≧c>0. In such embodiment, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) may be represented by the general formula (I-2):

RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)  (I-2)

wherein RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W; x>0, y≧0.5, x+y=3; 12.5≧z≧8.5, 3.5≧a+b>0, 3.0≧c>0.

In a preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.5≧x≧0.5, preferably 2.0≧x≧0.5, further preferably 1.2≧x≧1.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.0≧a≧0.5, preferably 1≧a≧0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 1.0≧b≧0.3; preferably 0.5≧b≧0.3.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 12.5≧z≧8.5, preferably 11.4≧z≧9, further preferably 11≧z≧10.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.5≧c≧0.1, preferably 1≧c≧0.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), 2.0≧x≧0.5, 2.0≧a≧0.5, 1.0≧b≧0.3, 2.5≧c≧0.1, 11.4≧z≧9.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes La and/or Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes La.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes Ce.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes mischmetal consisting of La and Ce, preferably the atomic ratio of La and Ce is 0.8:0.2.

In another preferred embodiment for the rare earth based hydrogen storage alloy represented by the general formula (I-2), RE denotes Lanthanum-rich mischmetal, La accounts for about 64 wt %, Ce accounts for about 25 wt %, Pr accounts for about 3 wt % and Nd accounts for about 8 wt %.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 12.5≧z≧11, 4≧a+b>0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≧0.5, x+y=3; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 12.5≧z≧11 (when z=11.4, the alloy is stoichiometric A₅B₁₉ type; when z≠11.4, the alloy is non-stoichiometric A₅B₁₉ type), 4≧a+b>0, 3.5≧c≧0, 2.5≧A+B>0;

preferably, 2.5≧x≧0.5, further preferably, 2.0≧x≧0.5;

preferably, 2.5≧a≧0, further preferably, 2.5≧a≧0.5;

preferably, 1.0≧b≧0, further preferably, 1.0≧b≧0.2, still further preferably, 0.5≧b≧0;

preferably, 2.5≧a≧0.5, 1.0≧b≧0.2;

preferably, 2.5≧c≧0, further preferably, 2.5≧c≧0.1, still further preferably, 0.5≧c≧0;

preferably, 1.0≧A≧0, further preferably, 1.0≧A≧0.1, still further preferably, 0.5≧A≧0.1;

preferably, 1.0≧B≧0, further preferably, 1.0≧B≧0.1, still further preferably, 0.3≧B≧0;

preferably, z=11.4.

In a preferably embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 2.0≧x≧0.5, 2.5≧a≧0.5, 1.0≧b≧0.2, 2.5≧c≧0.1, 1.0≧A≧0.1, 1.0≧B≧0.1, z=11.4.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 11>z≧9.5; 3.5≧a+b>0; 3≧c≧0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≧0.5, x+y=3; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 11>z≧9.5 (when z=10.5, the alloy is stoichiometric A₂B₇ type; when z≠10.5, the alloy is non-stoichiometric A₂B₇ type), 3.5≧a+b>0, 3≧c≧0, 2≧A+B>0;

preferably 2.5≧x≧0.5, further preferably 2.0≧x≧0.5;

preferably 2.0≧a≧0, further preferably 2.0≧a≧0.5, further preferably 1.0≧a≧0.5;

preferably 1.0≧b≧0, further preferably 1.0≧b≧0.2, further preferably 0.5≧b≧0;

preferably 2.0≧c≧0, further preferably 2.0≧c≧0.1, further preferably 0.5≧c≧0;

preferably 1.0≧A≧0.1, further preferably 0.5≧A≧0.1;

preferably 1.0≧B≧0.1, further preferably 0.3≧B≧0.1;

preferably 10.8≧z≧9.5, further preferably z=10.5.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 2.0≧x≧0.5, 2.0≧a≧0.5, 1.0≧b≧0.2, 2.0≧c≧0.1, 1.0≧A≧0.1, 1.0≧B≧0.1, z=10.5.

In a preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), 9.5>z≧8.5; 3≧a+b>0; 2.5≧c≧0.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm, Gd, x>0, y≧0.5, x+y=3; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V, W, 9.5>z≧8.5 (when z=9, the alloy is stoichiometric AB₃ type; when the alloy is non-stoichiometric AB₃ type), 3≧a+b>0, 2.5≧c≧0, 2≧A+B>0;

preferably 2.5≧x≧0.5, further preferably 2.0≧x≧0.5, further preferably 1.2≧x≧0.8, for example, x=1;

preferably 2.0≧a≧0, further preferably 2.0≧a≧0.5, further preferably 0.6≧a≧0.4, for example, a=0.5;

preferably 1.0≧b≧0, further preferably 1.0≧b≧0.2, further preferably 0.5≧b≧0;

preferably 2.0≧c≧0, further preferably 2.0≧c≧0.1, further preferably 0.5≧c≧0;

preferably 1.0≧A≧0, further preferably 1.0≧A≧0.1, further preferably 0.5≧A≧0.1;

preferably 1.0≧B≧0, further preferably 1.0≧B≧0.1, further preferably 0.3≧B≧0.2;

preferably 9.4≧z≧8.5, further preferably 9.4≧z≧9, further preferably z=9.

In another preferred embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), RE denotes one or more element(s) selected from La, Ce, Pr, Nd, Sm and Gd; M denotes one or more element(s) selected from Cu, Fe, Co, Sn, V and W, 2.0≧x≧0.5, 2.0≧a≧0.5, 1.0≧b≧0.2, 2.0≧c≧0.1, 1.0≧A≧0.1, 1.0≧B≧0.1, z=9.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), x may be 0.1, 0.2, 0.3 or 0.4, x may also be 0.5, 0.6 or 0.7, x may also be 0.8, 0.9 or 1, x may also be 1.1, 1.2 or 1.3, x may also be 1.4, 1.5 or 1.6, x may also be 1.7, 1.8 or 1.9, x may also be 2, 2.1 or 2.2, x may also be 2.3, 2.4 or 2.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), y may be 0.5, 0.6 or 0.7, y may also be 0.8, 0.9 or 1, y may also be 1.1, 1.2 or 1.3, y may also be 1.4, 1.5 or 1.6, y may also be 1.7, 1.8 or 1.9, y may also be 2, 2.1 or 2.2, y may also be 2.3, 2.4 or 2.5, y may also be 2.6, 2.7, 2.8 or 2.9.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), a may be 0, a may also be 0.1, 0.2, 0.3, 0.4 or 0.5, a may also be 0.6, 0.7, 0.8, 0.9 or 1, a may also be 1.1, 1.2, 1.3, 1.4 or 1.5, a may also be 1.6, 1.7, 1.8, 1.9 or 2, a may also be 2.1, 2.2, 2.3, 2.4 or 2.5, a may also be 2.6, 2.7, 2.8, 2.9 or 3.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), b may be 0, b may also be 0.1, 0.2 or 0.3, b may also be 0.4, 0.5 or 0.6, b may also be 0.7, 0.8 or 0.9, b may also be 1.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), z may be 8.5, 8.6, 8.7, 8.8, 8.9 or 9, z may also be 9.1, 9.2, 9.3, 9.4 or 9.5, z may also be 9.6, 9.7, 9.8, 9.9 or 10, z may also be 10.1, 10.2, 10.3, 10.4 or 10.5, z may also be 10.6, 10.7, 10.8, 10.9 or 11, z may also be 11.1, 11.2, 11.3, 11.4 or 11.5, z may also be 11.6, 11.7, 11.8, 11.9 or 12, z may also be 12.1, 12.2, 12.3, 12.4 or 12.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c may be 0, c may also be 0.1, 0.2, 0.3, 0.4 or 0.5, c may also be 0.6, 0.7, 0.8, 0.9 or 1, c may also be 1.1, 1.2, 1.3, 1.4 or 1.5, c may also be 1.6, 1.7, 1.8, 1.9 or 2, c may also be 2.1, 2.2, 2.3, 2.4 or 2.5, c may also be 2.6, 2.7, 2.8, 2.9 or 3, c may also be 3.1, 3.2, 3.3, 3.4 or 3.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A may be 0, A may also be 0.1, 0.2 or 0.3, A may also be 0.4, 0.5 or 0.6, A may also be 0.7, 0.8 or 0.9, A may also be 1.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), B may be 0, B may also be 0.1, 0.2 or 0.3, B may also be 0.4, 0.5 or 0.6, B may also be 0.7, 0.8 or 0.9, B may also be 1.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), x may be 0.5, 1, 1.2, 1.5, 2 or 2.5, x may also be 1, 1.2 or 1.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), y may be 0.5, 1, 1.5, 1.8, 2 or 2.5, y may also be 1.5, 1.8 or 2.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), a may be 0, 0.5, 0.8, 1, 1.5, 2, 2.5 or 3, a may also be 0.5, 0.8, 1, 1.5, 2 or 2.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), b may be 0, 0.2, 0.3, 0.5, 0.8, 1 or 1.5, b may also be 0, 0.2, 0.3 or 0.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), c may be 0, 0.1, 0.2, 0.5, 1, 1.5, 2 or 2.5, c may also be 0, 0.1 or 0.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), A may be 0, 0.1, 0.2, 0.3, 0.5 or 1, A may also be 0.1, 0.3 or 0.5.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), B may be 0, 0.1, 0.2, 0.3, 0.5 or 1, B may also be 0, 0.1, 0.2 or 0.3.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), when z=9, the alloy is stoichiometric AB₃ type; when the alloy is non-stoichiometric AB₃ type.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), when z=10.5, the alloy is stoichiometric A₂B₇ type; z≠10.5, the alloy is non-stoichiometric A₂B₇ type.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), when z=11.4, the alloy is stoichiometric A₅B₁₉ type; z≠11.4, the alloy is non-stoichiometric A₅B₁₉ type.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇, La₂Ni₇, LaNi₅, Ni₅Y, Ce₂Ni₇, Al₂Ni₆Y₃ and LaY₂Ni₉.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇, La₂Ni₇, LaNi₅ and Ce₂Ni₇.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇, La₂Ni₇, LaNi₅ and Al₂Ni₆Y₃.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇ and LaY₂Ni₉.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇ and La₂Ni₇, Ni₅Y.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises LaY₂Ni₉ phase.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), comprises one or more phase(s) selected from Y₂Ni₇ and La₂Ni₇.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) comprises Y₂Ni₇ phase.

In an embodiment for the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) has a maximum hydrogen storage capacity of 1.2˜1.5 wt %, preferably 1.3˜1.5 wt %, optionally 1.2˜1.4 wt % or 1.3˜1.4 wt %, at a temperature of 313K,

In an embodiment, when used as a negative material electrode for a Ni-MH battery, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) has a maximum discharge capacity of 300˜400 mAh/g, preferably 350˜400 mAh/g, further preferably 370˜400 mAh/g, still further preferably 380˜400 mAh/g, at a current density of 70 mA/g. The cut-off discharge voltage may be 1.0V.

In an embodiment, when used as a negative material electrode for a Ni-MH battery, the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) has a capacity retention of more than 85%, preferably more than 90%, more preferably more than 95%, still further preferably more than 98% after 100 cycles of charge and discharge, at a current density of 70 mA/g. The cut-off discharge voltage may be 1.0V.

According to the second aspect of the present application, provided is use of the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention as a hydrogen storage medium.

According to the third aspect of the present application, provided is use of the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention in manufacturing an electrode of a secondary battery.

The rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention may be manufactured into electrode, and the electrode could be made into a secondary battery coupled with other suitable materials. The secondary battery made from the rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention can be discharged and recharged for multiple times.

The rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention could be produced by a method comprising the following steps:

(i) providing raw materials according to the composition of the alloy product;

(ii) smelting the raw materials;

(iii) rapidly solidifying the smelted raw materials on a copper roller;

preferably, the linear speed of the copper roller in step (iii) is 3-4 m/s, and the copper roller is supplied with cooling water.

In an embodiment, in the method of preparing the rare earth based hydrogen storage alloy of the invention, after the step of rapidly solidifying, the prepared alloy is annealed at 700˜800° C. for 6˜10 hours, e.g. at 750° C. for 8 hours, under vacuum or inert gas.

In an embodiment, the hydrogen storage alloy of the invention may be produced by high temperature smelting-rapidly quenching method comprising the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching is 3.4 m/s. The copper roller is cooled with cooling water having a temperature of 25° C.

In an embodiment, in the method of preparing the rare earth based hydrogen storage alloy of the invention, the mass ratio of the raw materials which is prior to loss by burning are increased at an appropriate amount, the increase rate is shown in the following table:

raw material RE Y Mn Al increase rate 2% 1% 5% 3%

Besides the abovementioned methods, the hydrogen storage alloy represented by the general formula (I) of the invention may be produced by other methods for producing hydrogen storage alloys, such as: high-temperature smelting and casting method, mechanical alloying (MA) method, powder sintering method, high-temperature smelting and gas atomization method, reduction diffusion method, replacement-diffusion method, combustion synthesis (CS) method or self-propagating high temperature synthesis (SHS) method.

According to the fourth aspect of the invention, provided is the rare earth based hydrogen storage alloy represented by the general formula (I) as a hydrogen storage medium.

According to the fifth aspect of the invention, provided is the rare earth based hydrogen storage alloy represented by the general formula (I) for manufacturing an electrode of a secondary battery.

The rare earth based hydrogen storage alloy represented by the general formula (I) could be composited with other hydrogen storage alloys in various proportions to fabricate new hydrogen storage materials.

Heat treatment may be performed to improve the microstructures and properties of the rare earth based hydrogen storage alloy of the invention represented by the general formula (I), for example, to relieve structural stresses and eliminate component segregation, or to improve hydrogen absorption/desorption plateau characteristics or discharge/charge plateau characteristics, or to increase hydrogen storage capacity and cycle life. Various surface treatments may be performed to improve the alloy's performance, such as to improve the kinetics performance of hydrogen absorption/desorption processes or charge/discharge processes of the alloy, or to enhance the antioxidant ability of the alloy, or to improve the electrical/thermal conductivity of the alloy.

In the invention, unless otherwise specified, symbols for elements are consistent with the Periodic Table of Elements. In the general formula (I) of the invention, Y denotes yttrium, Ni denotes nickel, Mn denotes manganese, Al denotes aluminum, Zr denotes zirconium and Ti denotes titanium.

The Beneficial Effects of the Invention

The rare earth based hydrogen storage alloy of the invention represented by the general formula (I) of the invention has one or more of the following advantage(s):

(1) It has a favorable pressure-composition-temperature (P-c-T) feature. Under normal conditions, the hydrogen storage capacity could reach 1.28 wt % or more, the maximum hydrogen storage capacity of the alloy could reach 1.36 wt % or more;

(2) The electrochemical performance and hydrogen gas absorption and desorption performance of the rare earth based hydrogen storage alloy of the invention as hydrogen storage electrode are better than the traditional LaNi₅ type hydrogen storage alloy;

(3) The rare earth based hydrogen storage alloy of the invention doesn't contain magnesium, and therefore the preparation methods of the rare earth based hydrogen storage alloy of the invention is easier and safer compared to that of the traditional rare earth-magnesium-nickel hydrogen storage alloy

(4) The rare earth based hydrogen storage alloy of the invention has favorable activation performance, rate discharge ability, charging/discharging or hydrogen absorbing/desorbing cycling stability. It can work at a wide range of temperature and has a low self-discharge rate.

(5) One of the main components of the rare earth based hydrogen storage alloy of the invention is yttrium (Y). As Yttrium is abundant in rare earth minerals, the application of yttrium is beneficial for comprehensive utilization of rare earth resources of China.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are used to provide a further understanding of the invention and constitute a part of this application, in which:

FIG. 1-1 is an XRD pattern of the hydrogen storage alloy, LaCe_(0.5)Y_(1.5)Ni_(9.7)Mn_(0.5)Al_(0.3) (Example A23);

FIG. 1-2 is a redrawn XRD pattern of hydrogen storage alloy, LaCe_(0.5)Y_(1.5)Ni_(9.7)Mn_(0.5)Al_(0.3) according to the original XRD data of FIG. 1-1 (Example A23);

FIG. 1-3 is a P-c-T curve of the hydrogen storage alloy LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5) (Example A13);

FIG. 2-1 is a XRD pattern of the hydrogen storage alloy LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3) (Example B2);

FIG. 2-2 is a redrawn XRD pattern of the hydrogen storage alloy LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3) according to the original XRD data of FIG. 2-1 (Example B2);

FIG. 2-3 is a P-c-T curve of the hydrogen storage alloy LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3) (Example B2);

FIG. 3-1 is a XRD pattern of the hydrogen storage alloy LaY₂Ni₈Mn_(0.5)Al_(0.5) (Example C13);

FIG. 3-2 a redrawn XRD pattern of the hydrogen storage alloy LaY₂Ni₈Mn_(0.5)Al_(0.5) according to the original XRD data of FIG. 3-1 (Example C13);

FIG. 4-1 is a XRD pattern of the hydrogen storage alloy La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5) (Example D28);

FIG. 4-2 a redrawn XRD pattern of the hydrogen storage alloy La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5), according to the original XRD data of FIG. 4-1 (Example D28);

FIG. 4-3 is a pressure-composition-temperature (P-c-T) curve of the alloy LaY₂Ni_(9.5)Mn_(0.5)Al_(0.3)Cu_(0.2) (Example D38);

FIG. 5-1 is an XRD pattern of the hydrogen storage alloy La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5)Zr_(0.1)Ti_(0.1) (Example E18);

FIG. 5-2 an redrawn XRD pattern of the hydrogen storage alloy, La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5)Zr_(0.1)Ti_(0.1), according to the original XRD data of FIG. 5-1 (Example E18);

FIG. 6-1 is an X ray diffraction pattern of the alloy LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3)Zr_(0.1) (Example F35);

FIG. 7-1 is an XRD pattern of the hydrogen storage alloy, LaY₂Ni_(8.3)Mn_(0.5)Al_(0.2)Zr_(0.1) (Example G18);

FIG. 7-2 a redrawn XRD pattern of the hydrogen storage alloy, LaY₂Ni_(8.3)Mn_(0.5)Al_(0.2)Zr_(0.1), according to the original XRD data of FIG. 7-1 (Example G18).

DETAILED DESCRIPTION OF THE EMBODIMENT

The embodiments of the invention are further described with reference to the examples and drawings. The examples and the descriptions thereof are to illustrate the invention, yet not to limit the invention.

In the following examples:

1. phase structure analyses are performed on X-Ray Diffractometer (XRD), with the following test condition: Cu target, Ka radiation, tube voltage 40 kV, tube current 100 mA, scanning angle 2θ: 20˜80°, scanning speed: 3°/min and scanning step: 0.02°.

2. Equipments for measuring hydrogen storage amount include a PCT measuring instrument for hydrogen storage alloy, a thermostatic water bath and an analytical balance. The purity of the hydrogen used in the test is 99.999%.

Measuring procedure includes: crushing the alloy plates, sieving the crushed alloy with a 14 mesh (1200 μm) screen and a 200 mesh (74 μm) screen, collecting about 2.5 g of the alloy powder passing through 200 mesh screen and putting it into a sample container, vacuuming the sample container for 5 min, then charging the container with hydrogen, calibrating the volume of the sample container according to the ideal-gas equation, then vacuuming the sample container for 30 min, keeping the pressure below 0.001 MPa, activating the alloy for 3 times at 353K, then vacuuming the sample container for 2 h, and obtaining a pressure-composition-temperature (PCT) curve at 313K.

3. The rare earth based hydrogen storage alloy is produced by high temperature smelting-rapidly quenching method, the method comprising the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching is 3.4 m/s. The copper roller is cooled with cooling water having a temperature of 25° C.

4. The electrochemical parameters involved in the following examples include: N, denoting the number of cycles; C_(max), denoting the maximum discharge capacity; S₁₀₀, denoting the capacity retention ratio after 100 cycles; HRD₃₅₀, reflecting the discharge ability under a discharge current density (I_(d)) of 350 mA·g⁻¹, LTD₂₄₃, denoting the capacity retention ratio at a temperature of 243K; SD₇₂, denoting the capacity retention ratio after the battery being stored for 72 hours (self discharge feature).

High-rate discharge capacity (HRD₃₅₀) mainly reflects the dynamics performance of the hydrogen storage electrodes. HRD₃₅₀ is calculated according to the following formula:

${HRD} = {\frac{C_{d}}{C_{d} + C_{60}} \times 100\%}$

wherein: C_(d) denotes the discharge capacity measured at a discharge current density (I_(d)) and a cut-off discharge voltage of 1.0V (vs. Ni(OH)₂/NiOOH counter electrode), C₆₀ denotes the residual discharge capacity measured at a discharge current density of I=60 mA·g⁻¹ and a cut-off voltage of 1.0V after the alloy electrode has been fully discharge at high discharge current density (I_(d)). HRD₃₅₀ denotes the HRD measured at a discharge current density (I_(d)) of 350 mA·g⁻¹ _(.)

LTD₂₄₃ reflects the discharge performance at a low temperature of 243K. The low temperature discharge performance (LTD) is calculated according to the following formula:

${LTD} = {\frac{C_{T}}{C_{298}} \times 100\%}$

In the formula: C_(T) denotes the maximum discharge capacity at a current density of 70 mA/g at a low temperature (243K), C₂₉₈ denotes the maximum discharge capacity at a current density of 70 mA/g at the normal temperature (298K).

SD₇₂ denotes the self-discharge rate measured after the battery has been rested for 72 hours. SD₇₂ reflects the self-discharge ability (charge retention ability). The test condition includes: measuring the discharge capacity C_(a) by charging a battery for 6 h at a rate of 0.2 C, resting the battery for 10 min, discharging the battery to 1.0V at a rate of 0.2 C, and then measuring the discharge capacity C_(b), by charging the battery at a rate of 0.2 C for 6 h, resting the battery for 72 h, discharging the battery to 1.0 V at a rate of 0.2 C, and then measuring the discharge capacity C_(c) by charging and discharging the battery at a rate of 0.2 C. SD₇₂, which denotes the charge retention ratio after the battery being rested for 72 h, is calculated by the following formula:

2C _(b)/(C _(a) +C _(c))×100%

Example A1˜A23

A₂B₇ type RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b) hydrogen storage alloys in Example A1˜A23 were produced by applying the high temperature smelting-rapidly quenching method.

The alloys in Example A13 and Example A14 were produced by using the same raw material composition. The alloy in Example A13 was produced by applying the above-mentioned high temperature smelting-rapidly quenching method, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy in Example A14 was also produced by applying the above-mentioned high temperature smelting-rapidly quenching method. Besides, an annealing step was added to the producing method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example A20 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The test method for electrodes includes: mechanically crushing the alloys of Example A1˜A23 into 200-300 mesh alloy powder, mixing the alloy powder with carbonyl nickel powder by a weight ratio of 1:4, tabletting the mixed powder with a pressure of 16 MPa to form φ15 mm a MH electrodes plate, placing an electrode plate between two pieces of nickel foams, meanwhile, placing nickel belts between the nickel foams as the battery tabs, pressing the nickel forms with a pressure of 16 MPa to form a hydrogen storage anode (MH electrode) for testing, spot welding the edge of the electrode to make sure the electrode and the nickel forms were in close contact.

An open two-electrode system was used to test the electrochemical performance, native electrode was MH electrode; positive electrode was sintered Ni(OH)₂/NiOOH electrode with surplus capacity; electrolyte was 6 mol·L⁻¹ KOH solution. The assembled battery was being rested for 24 h, and then tested on a LAND battery testing equipment employing galvanostatic method to test their electrochemical performance (such as activating times, maximum capacity, high rate discharge capacity HRD, cycling stability, etc.). The environmental temperature during the test is 298K. The charge current density was 70 mA·g⁻¹; the charging time was 6 h; the discharge current density was 70 mA·g⁻¹; the discharge cut-off voltage was 1.0V, the interval between each charge and discharge was 10 min.

The A₂B₇ type RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b) hydrogen storage alloys of Example A1˜A23 and their electrochemical performance are listed in Table 1.

TABLE 1 A₂B₇ type RE_(x)Y_(y)Ni_(z−a−b)Mn_(a)Al_(b) hydrogen storage alloy and their electrochemical performance electrochemical performances C_(max) S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ A1 LaY₂Ni_(8.7)Mn_(0.5)Al_(0.3) 3 381 95 93 81 80 A2 LaY₂Ni_(9.7)Mn_(0.5)Al_(0.3) 2 386 93 91 82 83 A3 LaY₂Ni₁₀Mn_(0.5)Al_(0.3) 2 375 93 91 86 84 A4 LaY₂Ni₁₀Mn_(0.5) 2 378 93 93 82 81 A5 LaY₂Ni_(9.5)Mn 1 367 91 90 85 82 A6 La_(0.5)Y_(2.5)Ni_(9.5)Mn 1 352 95 92 87 81 A7 La_(0.5)Y_(2.5)Ni_(9.5)Al 3 337 98 87 85 86 A8 La₂YNi_(9.5)Mn 3 365 88 89 82 85 A9 La_(2.5)Y_(0.5)Ni_(9.5)Mn 3 351 85 85 79 87 A10 LaY₂Ni₁₀Al_(0.5) 3 346 98 91 85 83 A11 LaY₂Ni_(9.3)MnAl_(0.2) 1 352 93 90 86 83 A12 LaY₂Ni₉MnAl_(0.5) 2 349 96 87 83 85 A13 LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5) 2 362 90 89 84 80 A14 LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5) 3 369 92 91 86 83 A15 LaY_(1.5)Ce_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5) 3 357 93 88 81 83 A16 LaY_(1.5)Sm_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5) 3 343 95 91 86 85 A17 La_(0.8)Ce_(0.2)Y₂Ni_(9.5)Mn_(0.5)Al_(0.5) 3 363 93 90 85 80 A18 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5) 3 354 96 84 83 80 A19 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5) 3 352 97 82 83 81 A20 MlY₂Ni_(9.5)Mn_(0.5)Al_(0.5) 3 352 96 90 85 83 A21 La_(0.8)Ce_(0.2)Y₂Ni_(8.5)Mn_(1.5)Al_(0.5) 3 353 92 88 86 82 A22 La_(0.8)Ce_(0.2)Y₂Ni_(7.5)Mn_(2.5)Al_(0.5) 3 342 93 82 87 85 A23 LaCe_(0.5)Y_(1.5)Ni_(9.7)Mn_(0.5)Al_(0.3) 3 361 90 85 87 86

According to Table 1, compared with the LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5) alloy of Example A13, the alloy electrode of Example A14, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaCe_(0.5)Y_(1.5)Ni_(9.7)Mn_(0.5)Al_(0.3) alloy of Example A23 was analyzed by an X-ray diffractometer. FIG. 1-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 1-1, the alloy may contains Ce₂Ni₇ phase, Y₂Ni₇ phase, LaNi₅ phase, LaY₂Ni₉ phase or La_(0.5)Ce_(0.5)Y₂Ni₉ phase.

FIG. 1-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example A23. As shown in the figure, the alloy contains Y₂Ni₇ phase, La₂Ni₇ phase, LaNi₅ phase and Ce₂Ni₇ phase.

FIG. 1-3 is a pressure-composition-temperature curve (P-c-T curve) of LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5) alloy of Example A13 measured at 313K by applying Sievert method. As shown in FIG. 1-3, the maximum hydrogen storage capacity of the alloy could reach 1.36 wt % and the hydrogen desorption plateau pressure is about 0.05 MPa. The A31212482001 curve denotes the hydrogen absorption curve of the alloy and the D31212482001 curve denotes the hydrogen desorption curve of the alloy.

Example B1˜B22

The A₅B₁₉ type RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b) of Example B1˜B22 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example B13 and Example B14 were prepared from the same raw materials. The alloy of Example B13 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example B14 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately, (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example B20 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The A₅B₁₉ type RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b) hydrogen storage alloys of Example B1˜B22 and their electrochemical performance are listed in the following table.

TABLE 2 A₅B₁₉ type RE_(x)Y_(y)Ni_(z−a−b)Mn_(a)Al_(b) hydrogen storage alloy and their electrochemical performance electrochemical performances C_(max) S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ B1 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.3) 3 372 93 95 80 83 B2 LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3) 2 383 90 91 82 81 B3 LaY₂Ni_(11.7)Mn_(0.5)Al_(0.3) 2 365 95 90 83 85 B4 LaY₂Ni_(10.6)Mn_(0.8) 2 376 93 93 80 82 B5 LaY₂Ni_(9.9)Mn_(1.5) 1 367 91 90 85 81 B6 La_(0.5)Y_(2.5)Ni_(9.9)Mn_(1.5) 3 351 94 93 87 82 B7 La_(2.0)YNi_(9.9)Mn_(1.5) 2 361 92 89 84 85 B8 La_(2.5)Y_(0.5)Ni_(9.9)Mn_(1.5) 1 353 89 87 80 87 B9 LaY₂Ni_(9.9)Al_(1.5) 3 330 98 88 83 89 B10 LaY₂Ni_(10.6)Al_(0.8) 3 342 96 91 87 83 B11 LaY₂Ni_(9.4)Mn_(1.5)Al_(0.5) 1 362 93 90 83 80 B12 LaY₂Ni_(10.1)MnAl_(0.3) 2 383 90 87 85 82 B13 LaY₂Ni_(9.9)MnAl_(0.5) 2 380 92 89 81 80 B14 LaY₂Ni_(9.9)MnAl_(0.5) 3 383 93 91 86 83 B15 LaY_(1.5)Ce_(0.5)Ni_(9.9)MnAl_(0.5) 3 372 96 88 81 85 B16 LaY_(1.5)Sm_(0.5)Ni_(9.9)MnAl_(0.5) 3 363 95 90 85 83 B17 La_(0.8)Ce_(0.2)Y₂Ni_(9.9)MnAl_(0.5) 3 370 93 90 82 80 B18 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni_(9.9)MnAl_(0.5) 3 354 96 87 85 83 B19 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni_(9.9)MnAl_(0.5) 3 351 97 87 83 85 B20 MlY₂Ni_(9.9)MnAl_(0.5) 3 360 94 90 81 82 B21 La_(0.8)Ce_(0.2)Y₂Ni_(9.4)Mn_(1.5)Al_(0.5) 3 362 91 87 85 83 B22 La_(0.8)Ce_(0.2)Y₂Ni_(7.9)Mn₃Al_(0.5) 3 350 93 82 86 85

According to Table 2, compared with the LaY₂Ni_(9.9)MnAl_(0.5) alloy of Example B13, the alloy electrode of Example B14, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3) alloy (Example B2) was analyzed by an X-ray diffractometer. FIG. 2-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 2-1, the alloy may contain MnNi₈Y₃ phase, YNi_(3.912)Al_(1.088) phase, LaNi₅ phase, Ni₇Y₂ phase, or LaY₂Ni₉ phase, etc. The alloy may also contain YNi₃ phase, Y₂Ni₇ phase, LaY₂Ni₉ phase, LaNi₅ phase, Pr₅Co₁₉ phase or Ce₅Co₁₉ phase, etc.

FIG. 2-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example B2. As shown in the figure, the alloy contains Y₂Ni₇, La₂Ni₇, LaNi₅ and Al₂Ni₆Y₃ phase.

FIG. 2-3 is a pressure-composition-temperature curve (P-c-T curve) of LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3) alloy (Example B2) measured at 313K by applying Sievert method. As shown in FIG. 2-3, the maximum hydrogen storage capacity of the alloy could reach 1.33 wt % and the hydrogen desorption plateau pressure is about 0.1 MPa. The A32512333001 curve in denotes the hydrogen absorption curve of the alloy and D32512333001 curve denotes the hydrogen desorption curve of the alloy.

Example C1˜C22

The AB₃ type RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b) hydrogen storage alloy of Example C1˜C22 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example C13 and Example C14 were prepared from the same raw materials. The alloy of Example C13 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example C14 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example C20 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_(x)Y_(y)Ni_(z-a-b)Mn_(a)Al_(b) hydrogen storage alloys of Example C1˜C22 and their electrochemical performance are listed in the following table 3.

TABLE 3 RE_(x)Y_(y)Ni_(z−a−b)Mn_(a)Al_(b) hydrogen storage alloy and their electrochemical performance electrochemical performances C_(max) S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ C1 LaY₂Ni_(7.7)Mn_(0.5)Al_(0.3) 2 345 92 89 80 81 C2 LaY₂Ni_(8.2)Mn_(0.5)Al_(0.3) 2 362 93 91 81 83 C3 LaY₂Ni_(8.5)Mn_(0.5)Al_(0.3) 3 369 95 93 82 80 C4 LaY₂Ni_(8.5)Mn_(0.5) 2 367 93 93 80 78 C5 LaY₂Ni₈Mn 1 357 91 90 80 82 C6 La_(0.5)Y_(2.5)Ni₈Mn 3 351 97 93 85 80 C7 La_(2.0)YNi₈Mn 2 359 95 89 82 82 C8 La_(2.5)Y_(0.5)Ni₈Mn 1 354 91 87 79 85 C9 LaY₂Ni₈Al 3 342 98 87 81 85 C10 LaY₂Ni_(8.5)Al_(0.5) 3 339 98 91 81 83 C11 LaY₂Ni_(7.7)MnAl_(0.2) 1 342 93 90 83 83 C12 LaY₂Ni_(7.5)MnAl_(0.5) 2 332 96 87 81 85 C13 LaY₂Ni₈Mn_(0.5)Al_(0.5) 2 352 90 89 80 80 C14 LaY₂Ni₈Mn_(0.5)Al_(0.5) 3 362 91 92 83 82 C15 LaY_(1.5)Ce_(0.5)Ni₈Mn_(0.5)Al_(0.5) 3 345 93 88 82 85 C16 LaY_(1.5)Sm_(0.5)Ni₈Mn_(0.5)Al_(0.5) 3 335 95 92 80 86 C17 La_(0.8)Ce_(0.2)Y₂Ni₈Mn_(0.5)Al_(0.5) 3 357 92 90 80 82 C18 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni₈Mn_(0.5)Al_(0.5) 3 351 97 86 82 86 C19 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni₈Mn_(0.5)Al_(0.5) 3 348 98 87 82 87 C20 MlY₂Ni₈Mn_(0.5)Al_(0.5) 3 352 96 90 81 83 C21 La_(0.8)Ce_(0.2)Y₂Ni₇Mn_(1.5)Al_(0.5) 3 343 90 87 83 82 C22 La_(0.8)Ce_(0.2)Y₂Ni_(6.5)Mn₂Al_(0.5) 3 337 92 89 85 86

According to Table 3, compared with the LaY₂Ni₈Mn_(0.5)Al_(0.5) alloy of Example C13, the alloy electrode of Example C14, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni₈Mn_(0.5)Al_(0.5) alloy (Example C13) was analyzed by an X-ray diffractometer. FIG. 3-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 3-1, the alloy may contain MnNi₈Y₃ phase, Al_(0.20)LaNi_(2.80) phase or LaMn_(0.17)Ni_(2.83) phase, etc. The alloy may also contain YNi₃ phase or LaNi₃ phase, etc.

FIG. 3-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example C13. As shown in the figure, the alloy contains LaY₂Ni₉ phase or Ni₇Y₂ phase.

Example D1˜D38

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c) hydrogen storage alloy of Example D1˜D38 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example D7 and D8 as well as Example D28 and D29 were prepared from the same raw materials. The alloy of Example D7 and D28 were prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example D8 and D29 were prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example D37 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c) hydrogen storage alloys of Example D1˜D38 and their electrochemical performance are listed in the following table.

TABLE 4 RE_(x)Y_(y)Ni_(z−a−b−c)Mn_(a)Al_(b)M_(c)hydrogen storage alloy and their electrochemical performance electrochemical performances C_(max) S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N (mAh · g⁻¹) (%) (%) (%) SD₇₂ D1 LaY₂Ni_(6.5)MnAl_(0.5)Cu 3 352 95 93 81 83 D2 LaY₂Ni_(6.5)MnAl_(0.5)Fe 2 346 94 93 82 81 D3 LaY₂Ni_(6.5)MnAl_(0.5)Co 2 368 92 90 81 83 D4 LaY₂Ni_(6.5)MnAl_(0.5)Sn 2 356 93 92 80 80 D5 LaY₂Ni_(6.5)MnAl_(0.5)(VFe) 1 347 95 87 82 81 D6 LaY₂Ni_(6.5)MnAl_(0.5)W 3 352 93 90 78 80 D7 LaY₂Ni₈MnAl_(0.5)Cu 3 371 90 88 81 80 D8 LaY₂Ni₈MnAl_(0.5)Cu 2 376 92 91 83 82 D9 La_(0.5)Y_(2.5)Ni₈MnAl_(0.5)Cu 3 362 96 93 84 80 D10 La₂YNi₈MnAl_(0.5)Cu 2 367 90 87 80 82 D11 La_(2.5)Y_(0.5)Ni₈MnAl_(0.5)Cu 1 360 87 85 77 83 D12 LaY₂Ni₈MnAlCu 3 355 95 83 82 85 D13 LaY₂Ni₈MnAlCu_(0.1) 3 361 92 82 79 87 D14 LaY₂Ni₈MnAl_(0.5)Fe 2 363 93 90 81 81 D15 LaY₂Ni₈MnAl_(0.5)Co 2 378 90 92 83 82 D16 LaY₂Ni₈MnAl_(0.5)Sn 2 362 95 92 82 79 D17 LaY₂Ni₈MnAl_(0.5)(VFe) 1 357 93 90 82 81 D18 LaY₂Ni₈MnAl_(0.5)W 3 352 97 91 83 80 D19 LaY₂Ni_(9.9)MnAl_(0.5)Cu 3 365 91 90 81 82 D20 LaY₂Ni_(9.9)MnAl_(0.5)Fe 2 353 94 91 80 79 D21 LaY₂Ni_(9.9)MnAl_(0.5)Co 2 369 95 90 81 80 D22 LaY₂Ni_(9.9)MnAl_(0.5)Sn 2 356 96 92 78 82 D23 LaY₂Ni_(9.9)MnAl_(0.5)(VFe) 1 347 93 90 82 81 D24 LaY₂Ni_(9.9)MnAl_(0.5)W 3 342 98 91 84 83 D25 LaY₂Ni₉MnAl_(0.5)CoCu 3 352 95 93 85 83 D26 LaY₂Ni₅MnAl_(0.5)CuSn 2 349 96 91 82 81 D27 LaY₂Ni₈MnAl_(0.5)CoCuSn_(0.5) 2 354 95 90 78 80 D28 La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5) 2 372 90 89 81 79 D29 La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5) 3 377 92 91 84 82 D30 LaY₂Ni_(8.9)MnAl_(0.5)(VFe) 1 352 93 91 82 81 D31 LaY₂Ni_(8.9)MnAl_(0.5)W 3 339 98 91 85 83 D32 LaY_(1.5)Ce_(0.5)Ni₈MnAl_(0.5)Cu 3 363 92 89 83 82 D33 LaY_(1.5)Sm_(0.5)Ni₈MnAl_(0.5)Co 3 353 95 90 85 83 D34 La_(0.8)Ce_(0.2)Y₂Ni₈MnAl_(0.5)Fe 3 356 93 90 82 80 D35 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni₈MnAl_(0.5)Sn 3 334 97 90 85 83 D36 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni₈MnAl_(0.5)Sn 3 331 97 91 84 84 D37 MlY₂Ni_(7.7)MnAl_(0.3)CoCu_(0.5) 3 355 92 90 83 82 D38 LaY₂Ni_(9.5)Mn_(0.5)Al_(0.3)Cu_(0.2) 2 363 92 88 81 80

According to Table 4, compared with the alloys of Example D7 and D28 respectively, the alloy electrodes of Example D8 and D29, which have been subjected to annealing heat treatment, have increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5) alloy (Example D28) was analyzed by an X-ray diffractometer. FIG. 4-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 4-1, the alloy may mainly contain La₂Ni₇ phase.

FIG. 4-2 shows a redrawn XRD pattern of hydrogen storage alloy La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5) according to the original XRD data of Example D28. As shown in the figure, the alloy contains Y₂Ni₇ phase, La₂Ni₇ phase or Ni₅Y phase.

FIG. 4-3 is a pressure-composition-temperature curve (P-c-T curve) of LaY₂Ni_(9.5)Mn_(0.5)Al_(0.3)Cu_(0.2) alloy (Example D38) measured at 313K by applying Sievert method. As shown in FIG. 4-3, the maximum hydrogen storage capacity of the alloy could reach 1.28 wt % and the hydrogen desorption plateau pressure is about 0.03 MPa. The A32513142001 curve in denotes the hydrogen absorption curve of the alloy and D32513142001 curve denotes the hydrogen desorption curve of the alloy.

Example E1˜E34

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B) hydrogen storage alloy of Example E1˜E34 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example E14 and Example E15 were prepared from the same raw materials. The alloy of Example E14 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example E15 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example E28 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B) hydrogen storage alloys of Example E1˜E34 and their electrochemical performance are listed in the following table.

TABLE 5 RE_(x)Y_(y)Ni_(z−a−b−c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B)hydrogen storage alloy and their electrochemical performance electrochemical performances S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N C_(max)mAh · g⁻¹ (%) (%) (%) SD₇₂ E1 LaY₂Ni_(8.7)Mn_(0.5)Al_(0.3)Zr_(0.5)Ti_(0.3) 3 386 96 92 79 82 E2 LaY₂Ni_(9.7)Mn_(0.5)Al_(0.3)Zr_(0.5)Ti_(0.3) 2 389 94 92 82 83 E3 LaY₂Ni₁₀Mn_(0.5)Al_(0.3)Zr_(0.3)Ti_(0.2) 2 382 93 91 80 81 E4 LaY₂Ni₁₀Mn_(0.5)Zr_(0.5)Ti_(0.3) 2 387 91 90 82 79 E5 La_(0.5)Y_(2.5)Ni₁₀Mn_(0.5)Zr_(0.5)Ti_(0.3) 3 373 95 93 84 82 E6 La₂YNi₁₀Mn_(0.5)Zr_(0.5)Ti_(0.3) 2 379 92 91 81 80 E7 La_(2.5)Y_(0.5)Ni₁₀Mn_(0.5)Zr_(0.5)Ti_(0.3) 1 381 89 87 78 81 E8 LaY₂Ni_(9.5)MnZr_(0.5)Ti_(0.3) 1 373 92 90 83 81 E9 LaY₂Ni₉Mn_(1.5)Zr_(0.5)Ti_(0.3) 2 365 91 87 79 83 E10 LaY₂Ni_(8.5)Mn₂Zr_(0.5)Ti_(0.3) 3 359 89 85 75 84 E11 LaY₂Ni₁₀Al_(0.5)Zr_(0.5)Ti_(0.3) 3 352 96 90 79 82 E12 LaY₂Ni_(9.2)MnAl_(0.3)Zr_(0.5)Ti_(0.3) 1 360 92 89 81 80 E13 LaY₂Ni₉MnAl_(0.5)Zr_(0.5)Ti_(0.3) 2 354 94 89 82 83 E14 LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.5)Ti_(0.3) 2 367 92 90 79 80 E15 LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.5)Ti_(0.3) 3 375 93 92 83 83 E16 LaY₂Ni₉Mn_(0.5)AlZr_(0.5)Ti_(0.3) 3 366 97 90 80 85 E17 La_(1.2)Y_(1.8)Ni_(9.6)Mn_(0.5)Al_(0.3)Co_(0.1)Zr_(0.1)Ti_(0.1) 2 378 91 93 80 77 E18 La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5)Zr_(0.1)Ti_(0.1) 3 371 93 91 79 80 E19 La_(1.2)Y_(1.8)Ni_(8.7)Mn_(0.5)Al_(0.3)CoZr_(0.1)Ti_(0.1) 3 362 95 88 76 82 E20 La_(1.2)Y_(1.8)Ni_(7.7)Mn_(0.5)Al_(0.3)Co₂Zr_(0.1)Ti_(0.1) 4 351 98 85 72 85 E21 LaY_(1.5)Ce_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.5) 3 363 95 90 82 85 E22 LaY_(1.5)Ce_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5)Zr 5 342 98 87 80 86 E23 LaY_(1.5)Sm_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5)Ti_(0.5) 3 349 93 91 80 82 E24 LaY_(1.5)Sm_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5)Ti 4 337 97 89 81 85 E25 La_(0.8)Ce_(0.2)Y₂Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.3)Ti_(0.2) 3 370 95 91 82 81 E26 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.2) 3 362 95 88 78 79 E27 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.2) 3 359 96 90 80 81 E28 MlY₂Ni_(9.5)Mn_(0.5)Al_(0.5)Ti_(0.2) 3 357 93 91 80 81 E29 LaY₂Ni_(9.3)Mn_(0.5)Al_(0.2)Cu_(0.5)Zr_(0.3)Ti_(0.2) 3 374 92 92 81 82 E30 LaY₂Ni_(9.3)Mn_(0.5)Al_(0.2)Fe_(0.5)Zr_(0.5) 2 369 95 91 83 82 E31 LaY₂Ni_(9.3)Mn_(0.5)Al_(0.2)Co_(0.5)Zr_(0.3)Ti_(0.2) 2 387 93 90 83 81 E32 LaY₂Ni_(9.3)Mn_(0.5)Al_(0.2)Sn_(0.5)Ti_(0.3) 2 366 93 92 82 80 E33 LaY₂Ni_(9.3)Mn_(0.5)Al_(0.2)(VFe)_(0.5)Zr_(0.3) 2 361 95 91 80 81 E34 LaY₂Ni_(9.3)Mn_(0.5)Al_(0.2)W_(0.5)Zr_(0.3) 3 355 96 90 82 80

According to Table 5, compared with the LaY₂Ni_(9.5)Mn_(0.5)Al_(0.5)Zr_(0.5)Ti_(0.3) alloy of Example E14, the alloy electrode of Example E15, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the La_(1.2)Y_(1.8)Ni_(9.2)Mn_(0.5)Al_(0.3)Co_(0.5)Zr_(0.1)Ti_(0.1) alloy (Example E18) was analyzed by an X-ray diffractometer. FIG. 5-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 5-1, the alloy may contain La₂Ni₇ phase, LaY₂Ni₉ phase, Y₂Ni₇ phase, Ni₅La phase or LaNi₅ phase, etc. The alloy may also contain Ce₂Ni₇ or Y₂Ni₇ phase.

FIG. 5-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example E18. As shown in the figure, the alloy contains Y₂Ni₇, La₂Ni₇, Ni₅Y phase.

Example F1˜F35

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B) hydrogen storage alloy of Example F1˜B35 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example F12 and Example F13 were prepared from the same raw materials. The alloy of Example F12 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount) wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example F13 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example F24 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B) hydrogen storage alloys of Example F1˜F35 and their electrochemical performance are listed in the following table 6.

TABLE 6 RE_(x)Y_(y)Ni_(z−a−b−c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B)hydrogen storage alloy and their electrochemical performance electrochemical performances S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N C_(max)mAh · g⁻¹ (%) (%) (%) SD₇₂ F1 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.3)Zr_(0.5)Ti_(0.3) 3 377 95 92 83 80 F2 LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3)Zr_(0.5)Ti_(0.3) 2 387 93 90 82 81 F3 LaY₂Ni_(11.7)Mn_(0.5)Al_(0.3)Zi_(0.3)Ti_(0.2) 2 371 95 91 80 85 F4 LaY₂Ni_(10.6)Mn_(0.8)Zr_(0.5)Ti_(0.3) 2 380 94 92 82 82 F5 La_(0.5)Y_(2.5)Ni_(10.6)Mn_(0.8)Zr_(0.5)Ti_(0.3) 3 374 96 93 85 77 F6 La₂YNi_(10.6)Mn_(0.8)Zr_(0.5)Ti_(0.3) 2 383 89 90 81 83 F7 La_(2.5)Y_(0.5)Ni_(10.6)Mn_(0.8)Zr_(0.5)Ti_(0.3) 1 377 88 87 78 85 F8 LaY₂Ni_(9.9)Mn_(1.5)Zr_(0.5)Ti_(0.3) 1 375 93 91 85 82 F9 LaY₂Ni_(10.6)Al_(0.8)Zr_(0.5)Ti_(0.3) 3 353 98 92 85 83 F10 LaY₂Ni_(9.4)Mn_(1.5)Al_(0.5)Zr_(0.5)Ti_(0.3) 1 369 95 91 83 83 F11 LaY₂Ni_(10.1)MnAl_(0.3)Zr_(0.5)Ti_(0.3) 2 388 93 89 85 82 F12 LaY₂Ni_(9.9)MnAl_(0.5)Zr_(0.5)Ti_(0.3) 2 385 92 91 83 82 F13 LaY₂Ni_(9.9)MnAl_(0.5)Zr_(0.5)Ti_(0.3) 3 387 93 93 85 83 F14 LaY₂Ni_(8.9)Mn₂Al_(0.5)Zr_(0.5)Ti_(0.3) 2 375 92 90 82 85 F15 LaY₂Ni_(8.4)Mn_(2.5)Al_(0.5)Zr_(0.5)Ti_(0.3) 2 371 91 88 81 86 F16 LaY₂Ni_(9.9)MnAl_(0.5)ZrTi_(0.3) 4 357 98 92 86 87 F17 LaY_(1.5)Ce_(0.5)Ni_(9.9)MnAl_(0.5)Zr_(0.5) 3 380 95 90 83 82 F18 LaY_(1.5)Sm_(0.5)Ni_(9.9)MnAl_(0.5)Ti_(0.5) 3 365 94 90 82 81 F19 LaY_(1.5)Sm_(0.5)Ni_(9.9)MnAl_(0.5)Ti 4 357 96 91 83 79 F20 La_(0.8)Ce_(0.2)Y₂Ni_(9.9)MnAl_(0.5)Zr_(0.3)Ti_(0.2) 3 378 92 90 85 83 F21 La_(0.8)Ce_(0.2)Y₂Ni_(9.4)MnAlZr_(0.3)Ti_(0.2) 4 361 97 83 80 85 F22 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni_(9.9)MnAl_(0.5)Zr_(0.2) 3 357 96 89 84 80 F23 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni_(9.9)MnAl_(0.5)Zr_(0.2) 3 358 96 90 85 82 F24 MlY₂Ni_(9.9)MnAl_(0.5)Ti_(0.2) 3 363 96 91 82 82 F25 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.2)Cu_(0.5)Zr_(0.3)Ti_(0.2) 3 370 93 90 82 80 F26 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.2)Fe_(0.5)Zr_(0.5) 2 358 96 90 83 81 F27 LaY₂Ni_(10.6)Mn_(0.5)Al_(0.2)Co_(0.1)Zr_(0.3)Ti_(0.2) 1 377 92 93 84 78 F28 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.2)Co_(0.5)Zr_(0.3)Ti_(0.2) 2 374 95 91 82 80 F29 LaY₂Ni_(9.7)Mn_(0.5)Al_(0.2)CoZr_(0.3)Ti_(0.2) 3 362 96 88 79 82 F30 LaY₂Ni_(8.7)Mn_(0.5)Al_(0.2)Co₂Zr_(0.3)Ti_(0.2) 4 351 97 85 75 83 F31 LaY₂Ni_(8.2)Mn_(0.5)Al_(0.2)Co_(2.5)Zr_(0.3)Ti_(0.2) 4 342 98 81 71 85 F32 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.2)Sn_(0.5)Ti_(0.3) 2 361 95 90 81 79 F33 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.2)(VFe)_(0.5)Zr_(0.3) 1 356 95 91 83 82 F34 LaY₂Ni_(10.2)Mn_(0.5)Al_(0.2)W_(0.5)Zr_(0.3) 3 350 98 92 84 83 F35 LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3)Zr_(0.1) 1 377 93 93 85 83

According to Table 6, compared with the LaY₂Ni_(9.9)MnAl_(0.5)Zr_(0.5)Ti_(0.3) alloy of Example F12, the alloy electrode of Example F13, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni_(10.6)Mn_(0.5)Al_(0.3)Zr_(0.1) alloy (Example F35) was analyzed by an X-ray diffractometer. FIG. 6-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 6-1, the alloy may contain Y₂Ni₇ phase, La₂Ni₇ phase, Pr₅Co₁₉ phase, Ce₅Co₁₉ phase or LaNi₅ phase.

Example G1˜G34

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B) hydrogen storage alloy of Example G1˜G34 were prepared by adopting the high-temperature smelting rapidly quenching method.

The alloy of Example G15 and Example G16 were prepared from the same raw materials. The alloy of Example G15 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount), wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C.

The alloy of Example G16 was prepared by applying the abovementioned high-temperature smelting rapidly quenching method. Additionally, an annealing heat treatment step was added in the preparing process. Specifically, the method including the following steps: providing components satisfying the stoichiometric ratio of the chemical formula by weighing each raw material accurately (the raw materials with high burning loss were increased by appropriate amount) wherein the purity of each elemental metal or intermediate alloy used as raw material is greater than 99.0%; putting the raw materials into an Al₂O₃ crucible in sequence, vacuuming the crucible to a pressure of 3.0 Pa, and then filling the crucible with an inert gas Ar to a pressure of 0.055 MPa; smelting the raw materials, keeping the temperature of the smelted raw materials for about 6 minutes and then performing rapidly quenching. The linear speed of the copper roller used for rapidly quenching was 3.4 m/s. The copper roller was cooled with cooling water having a temperature of 25° C. The rapidly solidified alloy sheet was further annealed at 750° C. for 8 h under vacuum or inert gas atmosphere.

The Ml in Example G25 denotes Lanthanum-rich mischmetal, La accounted for about 64%, Ce accounted for about 25%, Pr accounted for about 3% and Nd accounted for about 8%.

The method for preparing the test electrode was same as that of Example A1˜A23.

The method for testing electrochemical performance was same as that of Example A1˜A23.

The RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B) hydrogen storage alloys of Example G1˜G34 and their electrochemical performance are listed in the following table.

TABLE 7 RE_(x)Y_(y)Ni_(z−a−b−c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B)hydrogen storage alloy and their electrochemical performance electrochemical performances S₁₀₀ HRD₃₅₀ LTD₂₄₃ Example hydrogen storage alloy N C_(max)mAh · g⁻¹ (%) (%) (%) SD₇₂ G1 LaY₂Ni_(7.7)Mn_(0.5)Al_(0.3)Zr_(0.5)Ti_(0.3) 2 353 96 91 80 80 G2 LaY₂Ni_(8.2)Mn_(0.5)Al_(0.3)Zr_(0.5)Ti_(0.3) 2 367 93 90 79 81 G3 LaY₂Ni_(8.5)Mn_(0.5)Al_(0.3)Zr_(0.3)Ti_(0.2) 3 375 92 91 77 80 G4 La_(0.5)Y_(2.5)Ni_(8.5)Mn_(0.5)Al_(0.3)Zr_(0.3)Ti_(0.2) 4 351 97 94 81 76 G5 La₂YNi_(8.5)Mn_(0.5)Al_(0.3)Zr_(0.3)Ti_(0.2) 2 363 93 89 75 79 G6 LaY₂Ni_(8.9)Mn_(0.5)Zr_(0.1)Ti_(0.3) 1 374 90 92 81 77 G7 LaY₂Ni_(8.5)Mn_(0.5)Zr_(0.5)Ti_(0.3) 2 372 93 92 78 79 G8 LaY₂Ni₈Mn_(0.5)ZrTi_(0.3) 3 365 97 87 73 81 G9 LaY₂Ni₈MnZr_(0.5)Ti_(0.3) 1 363 91 90 77 80 G10 LaY₂Ni_(7.5)Mn_(1.5)Zr_(0.5)Ti_(0.3) 2 359 90 87 74 83 G11 LaY₂Ni₇Mn₂Zr_(0.5)Ti_(0.3) 3 350 93 85 71 85 G12 LaY₂Ni_(8.5)Al_(0.5)Zr_(0.5)Ti_(0.1) 3 343 98 92 80 83 G13 LaY₂Ni_(7.7)MnAl_(0.3)Zr_(0.5)Ti_(0.3) 1 352 92 89 78 81 G14 LaY₂Ni_(7.5)MnAl_(0.5)Zr_(0.5)Ti_(0.3) 2 340 97 90 81 82 G15 LaY₂Ni₈Mn_(0.5)Al_(0.5)Zr_(0.5)Ti_(0.3) 2 359 91 89 79 82 G16 LaY₂Ni₈Mn_(0.5)Al_(0.5)Zr_(0.5)Ti_(0.3) 3 370 92 91 80 82 G17 LaY₂Ni_(7.5)Mn_(0.5)AlZr_(0.5)Ti_(0.3) 4 352 96 88 75 84 G18 LaY₂Ni_(8.3)Mn_(0.5)Al_(0.2)Zr_(0.1) 3 367 93 90 79 80 G19 LaY_(1.5)Ce_(0.5)Ni₈Mn_(0.5)Al_(0.5)Zr_(0.5) 3 351 94 89 77 80 G20 LaY_(1.5)Sm_(0.5)Ni₈Mn_(0.5)Al_(0.5)Ti_(0.5) 2 357 93 91 76 83 G21 LaY_(1.5)Sm_(0.5)Ni₈Mn_(0.5)Al_(0.5)Ti 3 348 96 93 80 82 G22 La_(0.8)Ce_(0.2)Y₂Ni₈Mn_(0.5)Al_(0.5)Zr_(0.3)Ti_(0.2) 3 368 92 91 79 80 G23 La_(0.8)Ce_(0.2)Y_(1.5)Sm_(0.5)Ni₈Mn_(0.5)Al_(0.5)Zr_(0.2) 3 355 95 88 80 79 G24 La_(0.8)Ce_(0.2)Y_(1.5)Nd_(0.5)Ni₈Mn_(0.5)Al_(0.5)Zr_(0.2) 3 352 96 90 81 80 G25 MlY₂Ni₈Mn_(0.5)Al_(0.5)Ti_(0.2) 3 359 96 91 78 80 G26 LaY₂Ni_(7.8)Mn_(0.5)Al_(0.2)Cu_(0.5)Zr_(0.3)Ti_(0.2) 3 363 93 94 82 81 G27 LaY₂Ni_(7.8)Mn_(0.5)Al_(0.2)Fe_(0.5)Zr_(0.5) 2 352 93 92 83 81 G28 LaY₂Ni_(8.2)Mn_(0.5)Al_(0.2)Co_(0.1)Zr_(0.3)Ti_(0.2) 2 375 90 89 84 80 G29 LaY₂Ni_(7.8)Mn_(0.5)Al_(0.2)Co_(0.5)Zr_(0.3)Ti_(0.2) 2 373 93 91 81 82 G30 LaY₂Ni_(7.3)Mn_(0.5)Al_(0.2)CoZr_(0.3)Ti_(0.2) 3 361 96 87 77 83 G31 LaY₂Ni_(6.3)Mn_(0.5)Al_(0.2)Co₂Zr_(0.3)Ti_(0.2) 4 348 98 82 73 85 G32 LaY₂Ni_(7.8)Mn_(0.5)Al_(0.2)Sn_(0.5)Ti_(0.3) 2 359 94 92 80 79 G33 LaY₂Ni_(7.8)Mn_(0.5)Al_(0.2)(VFe)_(0.5)Zr_(0.3) 1 352 96 89 82 80 G34 LaY₂Ni_(7.8)Mn_(0.5)Al_(0.2)W_(0.5)Zr_(0.3) 3 355 95 91 82 81

According to Table 7, compared with the LaY₂Ni₈Mn_(0.5)Al_(0.5)Zr_(0.5)Ti_(0.3) alloy of Example G15, the alloy electrode alloy of Example G16, which has been subjected to annealing heat treatment, has increased electrochemical capacity, and improved cycle life, discharge capacity, low temperature discharge characteristic, as well as self-discharge performance.

The microstructure of the LaY₂Ni_(8.3)Mn_(0.5)Al_(0.2)Zr_(0.1) alloy (Example G18) was analyzed by an X-ray diffractometer. FIG. 7-1 shows an XRD pattern exported from the X-ray diffractometer. As shown in FIG. 7-1, the alloy may contain LaY₂Ni₉ phase or LaNi phase.

FIG. 7-2 shows a redrawn XRD pattern of hydrogen storage alloy according to the original XRD data of Example G18. As shown in the figure, the alloy contain LaY₂Ni₉ phase.

Finally, it should be noted that the above embodiments are merely provided for describing the technical solutions of the present invention but not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those of ordinary skill in the art: the technical features of the present invention may still be modified or equivalent replacements may be made to some technical features; without departing from the spirit of the present invention, which should be covered in the scope of the technical solutions. 

1. A rare earth based hydrogen storage alloy represented by the general formula (I): RE_(x)Y_(y)Ni_(z-a-b-c)Mn_(a)Al_(b)M_(c)Zr_(A)Ti_(B)   (I) wherein RE denotes one or more element(s) selected from the group consisting of La, Ce, Pr, Nd, Sm, and Gd; M denotes one or more element(s) selected from the group consisting of Cu, Fe, Co, Sn, V, and W; x>0, y≧0.5, and x+y=3, 13≧z≧7; 6≧a+b>0, 5≧c≧0, and 4≧A+B≧0.
 2. The rare earth based hydrogen storage alloy according to claim 1, wherein x>0, y≧0.5, x+y=3; 12.5≧z≧8.5; 5.5≧a+b>0, 3.5≧c≧0, and 2.5≧A+B≧0.
 3. The rare earth based hydrogen storage alloy according to claim 2, wherein c=0 and A=B=0.
 4. The rare earth based hydrogen storage alloy according to claim 3, wherein 12.5≧z≧11.
 5. The rare earth based hydrogen storage alloy according to claim 3, wherein 11>z≧9.5; and 4.5≧a+b>0.
 6. The rare earth based hydrogen storage alloy according to claim 3, wherein 9.5>z≧8.5; and 3.5≧a+b>0.
 7. The rare earth based hydrogen storage alloy according to claim 2, wherein A=B=0, and c>0.
 8. The rare earth based hydrogen storage alloy according to claim 7, wherein 3.5≧a+b≧0; and 3.0≧c>0.
 9. The rare earth based hydrogen storage alloy according to claim 2, wherein 2.5≧A+B>0.
 10. The rare earth based hydrogen storage alloy according to claim 9, wherein 12.5≧z≧11, and 4≧a+b>0.
 11. The rare earth based hydrogen storage alloy according to claim 9, wherein 11>z≧9.5; 3.5≧a+b>0; and 3≧c≧0.
 12. The rare earth based hydrogen storage alloy according to claim 9, wherein 9.5<z≧8.5; 3≧a+b>0; and 2.5≧c≧0.
 13. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iv) apply: i) 2.0≧x≧0.5; ii) 3.0≧a≧0.5; iii) 1.5≧b≧0.3; iv) z=11.4.
 14. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iv) apply: i) 2.0≧x≧0.5; ii) 2.5≧a≧0.5; iii) 1.0≧b≧0.2; iv) z=10.5.
 15. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iv) apply: i) 2.0≧x≧0.5; ii) 2.0≧a≧0.5; iii) 1.0≧b≧0.2; iv) z=9.
 16. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-v) apply: i) 2.0≧x≧0.5; ii) 2.0≧a≧0.5; iii) 1.0≧b≧0.3; iv) 11.4≧z≧9; v) 2.5≧c≧0.1.
 17. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-vii) apply: i) 2≧x≧0.5; ii) 2.5≧a≧0.5; iii) 1.0≧b≧0.2; iv) z=11.4; v) 2.5≧c≧0.1; vi) 1.0≧A≧0.1; vii) 1.0≧B≧0.1.
 18. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-vii) apply: i) 2.0≧x≧0.5; ii) 2.0≧a≧0.5; iii) 1.0≧b≧0.2; iv) z=10.5; v) 2.0≧c≧0.1; vi) 1.0≧A≧0.1; vii) 1.0≧B≧0.1.
 19. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-vii) apply: i) 2.0≧x≧0.5; ii) 2.0≧a≧0.5; iii) 1.0≧b≧0.2; iv) z=9; v) 2.0≧c≧0.1; vi) 1.0≧A≧0.1; vii) 1.0≧B≧0.1.
 20. The rare earth based hydrogen storage alloy according to claim 1, wherein one or more of the following items i)-iii) apply: i) the alloy has a maximum hydrogen storage capacity of 1.2-1.5 wt % at 313K; ii) when utilized as a negative material electrode for a Ni-MH battery, the alloy has a maximum discharge capacity of 300-400 mAh/g at a current density of 70 mA/g; iii) the alloy has a capacity retention of more than 85%, at a current density of 70 mA/g. 21-22. (canceled)
 23. A hydrogen storage medium comprising the rare earth based hydrogen storage alloy according to claim
 1. 24. An electrode of a secondary battery comprising the rare earth based hydrogen storage alloy according to claim
 1. 25. A secondary battery comprising the rare earth based hydrogen storage alloy according to claim
 1. 